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Fred HansenThe Official Fred

Spring 05

Wei Qi, Baduk, Goa game of strategy

ChinaKorea

Japan & others

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Why play go?

• Fun• Challenge• Think differently

– not procedural

• A window to the orient • Only one rule

Warning: It takes time to “get” go

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What does go look like?

• Board with 19 x 19 lines• White and black stones in bowls• On your turn, put a stone on an intersection

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What is the goal?

• Get the most stones on the board– surround bigger empty space– keep groups alive

• The game ends whenneither player wants to play

– there’s no more space to grab

• In practice not all intersections are filled– when it is clear what color goes there

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How a game might begin

• Players take turns putting stones

black’s potential territory – 29 points

white’s potential territory – 38 points

• White is ahead

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How a game might end

• Neither player can gain points

black’s territory – 35 points

white’s territory – 46 points

• White wins

Cannot be part of an immortal group;effectively dead

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Could black do better?

• Second move too “low”

• Better to be higher; push white lower

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• A “liberty” is an empty intersection adjacent along a line

• A stone without liberties is dead– It is removed from the board

How does a stone die?

No liberties dead

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So, what is a liberty?

• A stone’s total liberties are– its own, plus

Liberties for the black stones

4 3 2

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6

• Empty intersections count only once

3 3 3

22

– those of adjacent same-color stones

When it is played, a stone’s own liberties are checked after making any captures.

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The board pattern must not repeat

• A move is illegal if it leaves a board identical to what it was ever before

• Hence: cannot recapture simple “ko”

One Rule: No repeat

If white captures,

black cannot recapture on the next turn

sometimes black makes a threat, white responds, & black recaptures

a “ko threat”

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• A group with two holes is immortal

Immortality

Black could capture only by playing in both holes.

• The possibility of two holes is enough

If black plays b, white plays a, and vice versa

ba

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“First capture”

• Goal – understand capture rules

• Method – play first capture– First player to capture a stone wins– 7 x 7 board makes it faster